facillllllllllllllllllllllllllllllllle

Sujet: facillllllllllllllllllllllllllllllllle Lun 22 Mar 2010, 08:07

calcule
P=(100-1) (100-2) (100-3) (100-4) ....................... (100-115)

on a a , b , c des nombres positif bref 0<a<b<c
prouve"que
2/va+vc=1/va+vb+1/vb+vc
v facillllllllllllllllllllllllllllllllle Icon_arrow

racine

Sujet: Re: facillllllllllllllllllllllllllllllllle Mar 23 Mar 2010, 20:44

Premier exercice:
P=(100-1)(100-2)(100-3)(100-4).......(100-115)
P=(100-1)(100-2)(100-3)......(100-100)...(100-115)
P=(100-1)(100-2)(100-3).........0.....(100-115)
P=0

Sujet: Re: facillllllllllllllllllllllllllllllllle Mar 23 Mar 2010, 21:05

Pour Le deuxieme exercice:
Il faut dire que a+c=2b

Sujet: Re: facillllllllllllllllllllllllllllllllle Mar 23 Mar 2010, 21:36

Deuxième exercice:
1/(Va+Vb)+1/(Vb+Vc)=(Va+2Vb+Vc)/(Va+Vb)(Vb+Vc)

2(Va+Vb)(Vb+Vc)=2(Vab+Vac+b+Vbc) (1)

(Va+Vc+2Vb)(Va+Vc)=a+Vac+2Vab+Vac+c+2Vbc
=a+c+2Vac+2Vab+2Vbc
=2b+2Vac+2Vab+2Vbc
=2(Vab+Vac+b+Vbc) (2)

De (1) et (2) on a :

(Va+Vc+2Vb)(Va+Vc)=2(Va+Vb)(Vb+Vc)

2/((Va+Vc)=(Va+2Vb+Vc)/(Va+Vb)(Vb+Vc)
2/(Va+Vc)=1/(Va+Vb)+1/(Vb+Vc)

@+
Dites si c'est juste ou pas

Sujet: Re: facillllllllllllllllllllllllllllllllle Mar 23 Mar 2010, 21:53

Wé c juste , Tu as utiliser 2b=a+c:

...=a+c+2Vac+2Vab+2Vbc
=2b+2Vac+2Vab+2Vbc

Sujet: Re: facillllllllllllllllllllllllllllllllle Mer 24 Mar 2010, 22:05

c juste il y a une autr facillllllllllllllllllllllllllllllllle Icon_idea

e façon

Sujet: Re: facillllllllllllllllllllllllllllllllle Mer 24 Mar 2010, 22:07

d 'autrrrrrrrrrrrrrrrrrrrrre reponses

Sujet: Re: facillllllllllllllllllllllllllllllllle Mer 24 Mar 2010, 22:07